Download Gross morphological studies on major salivary glands of prenatal

Buffalo Bulletin (July-September 2016) Vol.35 No.3
Original Article
GROSS MORPHOLOGICAL STUDIES ON MAJOR SALIVARY GLANDS
OF PRENATAL BUFFALO
K. Raja, M. Santhi Lakshmi*, G. Purushotham, K.B.P. Raghavender,
T.S. Chandrasekhara Rao and D. Pramod Kumar
ABSTRACT
morphological, salivary glands, mandibular duct
Gross morphological study was conducted
on the major salivary glands of 42 buffalo foetuses
ranging from 73 to 253 days. The mandibular gland
was the largest salivary gland during the prenatal
life. Dense compact lobulation of the parotid and
mandibular glands was observed first at 155 days of
foetal age. The mandibular gland was covered by the
confluence of linguo-facial, occipital and maxillary
veins laterally and developing thymus caudally
throughout the prenatal period. Differentiation of
dorsal and ventral parts of the sublingual gland was
observed at 108 days of foetal age.
Major salivary glands of various domestic
animals are paired structures, which includes
parotid, mandibular and sublingual glands.
Salivary glands fulfill important role in the oral
biology by producing saliva for lubrication, as
well as supplying electrolytes, mucus, antibacterial
compounds and various enzymes to the oral cavity.
Loss of salivary glands function can result in the
wide spread deterioration of oral health (Hsu
et al., 2010). Study of normal development of
salivary glands will be helpful for both anatomists
and clinicians as they are having important role
in several dreadful diseases like rabies, foot and
mouth disease and other viral diseases.
MATERIALS AND METHODS
The prenatal specimens of unknown age,
irrespective of the sex, nutritional status of the
mother were collected from slaughter houses the
CVRL (Curved Crown Rump Length) of specimens
was measured to estimate the age of by Soliman’s
(1975) formula. Gross morphological changes
were studied in feasible foetal age from of 73 days
to 253 days regarding shape, size, location and
relation of the parotid, mandibular and sublingual
salivary glands.
RESULTS AND DISCUSSION
The parotid gland was situated along the
caudal border of the masseter muscle extending
from the region of the external auditory canal to
the level above the angle of mandible. It was in the
form of a pyramid with loosely arranged multiple
lobules at 73 day foetal age. However the shape
of the gland was found to be evident as triangular
with a broad base and apex during 84 days to 253
days. Gradual change in the shape may be due to
growth of the gland during the prenatal life. The
base of the gland was superior with a notch placed
Keywords: buffaloes, Bubalus bubalis, Gross
Department of Veterinary Anatomy, College of Veterinary Science, Rajendranagar, Andhra Pradesh, India,
*E-mail: [email protected]
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around the external auditory canal, while the apex
was situated little above the angle of the mandible
(Figure 1). Subsequently the gland reached the
space between the base of the ear, vertical ramus
of the mandible and sterno-mandibularis muscle in
mid and late foetal stages (Figure 2).
The colour of the parotid gland varied
from light yellow to light brown during the prenatal
period, variation may be attributed to increased
vasculature to the gland. The weight of the parotid
foetuses of 36 to 53 days (Guizetti and Radlanski,
1996). The duct of the parotid gland was opened
into the mouth cavity at the level of upper 2nd
erupting cheek tooth till 145 days, the same was
evident at the level of upper erupting 3rd cheek
tooth from 155 days to 253 days of foetal life.
The mandibular gland was the largest
among the three major salivary glands in prenatal
buffalo, while the parotid gland was reported to be
the largest major salivary gland in human beings
during prenatal life (Attie and Sciubba, 1981).
It was long, narrow and curved throughout the
prenatal period (Figure 1).
The mandibular gland was light yellow
in colour during the prenatal period. It was long,
narrow and curved and extended from the region
of tympanic bulla to the level above the angle of
the mandible behind the parotid salivary gland in
early age groups (Figure 1). However the position
of the gland gradually changed to that of adult at
123 days, but it was located caudo-medial to the
parotid salivary gland as reported in day old kid by
Rauf et al. (2004) which continued throughout the
mid and late foetal age groups. The average length,
width and weight of the mandibular gland ranged
from 1.23 to 2.84 cm, 0.45 cm to 1.6 cm and 2.1 to
8.00 g respectively during the prenatal period from
84 to 253 days.
The mandibular gland was covered
laterally by fascia and the confluence of the
external jugular vein with maxillary, linguo-facial
and occipital veins (Figure 1), which agree partly
with the findings of Rauf et al. (2004) in one
day old kid. The gland was related to the larynx,
division of the common carotid artery, external
carotid artery, 9th ,10th and 11th cranial nerves,
gland ranged from 2.0 to 7.1 g during 84 to 253
days. The length and width of the parotid gland
ranged between 0.8 to 2.1cm and 0.5 to 2.4 cm
respectively from 84 to 253 days. Gradual increase
in length, width and weight of the gland was due
to increased proliferation of ducts, increased
lobulation and connective tissue formation during
the foetal stage. Compact lobulation and adult
characteristic features of the gland were attained at
155 days (Figure 3).
The lateral surface was covered by parotid
fascia, developing parotido - auricularis muscle
and a muscle extending from the zygomatic arch
to cervical fascia. The gland was reported to be
attached superiorly to the zygomatic arch. The
middle part of the gland was penetrated by the
maxillary vein from lateral to medial surface
throughout the prenatal life (Figure 1).
The medial surface was uneven and
related to great cornu of hyoid, digastricus,
occipito-hyoideus and sterno-mastoideus muscles,
external carotid artery, external jugular vein and
its tributaries, facial nerve and its branches. The
anterior border was in contact with the parotid lymph
node above and masseter muscle below throughout
the prenatal period (Figure 1). The medial surface
of the parotid gland showed impressions for the
mandibular salivary gland, parotid lymph node and
masseter muscle as reported in human embryos and
stylo-hyoideus muscle and great cornu of hyoid
medially and developing thymus caudally. The
anterior extremity was narrow and placed at the
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level of the angle of the mandible above the sternomandibularis muscle and the posterior extremity at
the level of fossa atlantis as reported in domestic
animals (Budras and Habel et al., 2003). However
the anterior extremity was carried to the level of
root of the tongue in mid and late age groups.
The mandibular gland showed loosely
arranged lobules at 73 days. Dense compact
lobulation of the gland was observed between 155
to 253 days of prenatal life (Figure 3). Mandibular
lymph node was placed above the anterior
extremity of the gland, a little cranial to or at the
angle of the mandible. At 253 days the mandibular
gland attained the characteristic shape, colour and
position to that of adult.
The mandibular duct was well developed
at 84 days but not amenable for dissection. It was
found to be leaving the gland at lower third of the
inferior border between 84 to 123 days and middle
of the concave border between 145 to 253 days.
The duct running on the floor of the mouth cavity in
close association with the sublingual duct opened
closely along the side of monostomatic sublingual
duct at the caruncula sublingualis.
The sublingual gland was the smallest
among the major salivary glands (Figure 3). It was
composed of two parts, the dorsal (polystomatic)
and ventral (monostomatic) parts. The dorsal and
ventral parts of the gland were distinguishable
at 108 days of foetal age. The dorsal part of the
gland was arranged in a chain of lobules from
the palato-glossal arch to the incisive part of the
mandible, while the ventral part was lying beneath
the mucosa of the floor of the mouth above the
mylohyoid muscle between the mandible laterally
and the muscles of tongue medially. The dorsal
and ventral parts of the gland were distinguished
at 108 days. The colour of the dorsal part varied
from light yellow to light brown during prenatal
development, while the ventral part appeared as
light yellow between 189 to 253 days of prenatal
life.
Figure 1. Photograph of 84 day buffalo foetal head showing parotid (P) and mandibular (M) salivary glands
and their relation to adjacent structures. PL- Parotid lymph node, EJ- External jugular vein, SMSterno-mandibularis, D-Dorsal buccal nerve, MA-Masseter muscle,E-External ear, T- Thymus.
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Figure 2. Photograph of 145 day buffalo foetus showing compact lobulation of parotid gland (P) and loosely
arranged lobules of mandibular (M) salivary glands. E- External auditory canal, EJ- Ext jugular
vein, T -Thymus,SM- Sterno mandibularis muscle, MA- Masseter muscle
Figure 3. Photograph showing dense compact lobulation in foetal parotid (P), mandibular (M), and sublingual
(L) salivary glands at 155 days in buffalo.
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The ventral part of the gland was elongated
and situated beneath the mucosa of the floor of the
mouth above the mylohyoideus muscle between
the mandible laterally and the muscles of tongue
medially. The ventral part of the sublingual gland
was drained by only one duct, which opened
along the side of mandibular duct at caruncula
sublingualis as reported by Latshaw (1987) in
domestic animals. But the ducts of the dorsal part
of sublingual gland were not visible to the naked
eye during the prenatal period.
The weight, length and width of the ventral
part of sublingual gland ranged from 1.45 g to 2.65
g, from 1.7 to 4.2 cm and 0.25 to 1.1 cm from 84
days to 253 days of embryonic life. Increase in the
size and weight of the gland was due to increased
proliferation of ducts, increased lobulation and
connective tissue formation.
Recent Progress and Future Opportunities.
Int. J. Oral. Sci., 2(3): 117-126.
Latshaw, W.K. 1987. The Veterinary Developmental
Anatomy. B.C. Decker Co., INC, Toronto.
p. 128-129.
Rauf, S.M.A., M.R. Islam and M.K. Anan. 2004.
Macroscopic and Microscopic study of the
mandibular salivary gland of black bengal
goats. Bang. J. Vet. Med., 2(2): 137-142.
Soliman, M.K. 1975. Studies on the physiological
chemistry of the allantoic and amniotic
fluids of buffaloes at the various periods of
pregnancy. Indian Vet. J., 52: 106-112.
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